The application relates generally to laser systems and more particularly to a system for synthesizing multiple pulses.
It is known to measure femtosecond laser pulses using a phase and amplitude modulator by programming phase and amplitude to achieve an autocorrelation. One such traditional device is disclosed in B. Vacano, et al., “Shaper-assisted Collinear SPIDER: fast and simple broadband pulse compression in nonlinear microscopy,” J. Opt. Soc. Am. B, vol. 24, no. 5, 1091 (May 2007). The phase and amplitude modulator device is expensive, and time consuming and difficult to set up accurately.
Conventional interferometric autocorrelation obtained by physical movement of optic components is disclosed in A. Weiner, “Review Article: Femtosecond pulse shaping using spatial light modulators,” Rev. Sci. Instrum., vol. 71, no. 5, 1930 (May 2000). Optical pulse train generation is also disclosed in U.S. Pat. No. 6,577,782 entitled “Direct Space-to-time Pulse Shaper and Optical Pulse Train Generator” which issued to Leaird and Weiner on Jun. 10, 2003, which is incorporated by reference herein. This patent recognizes difficulties in use of Fourier transform pulse shapers with high-bit-rate data telecommunications.
In accordance with the present invention, a laser pulse synthesis system is provided. A further aspect of the present system uses a phase-only modulator to measure ultrashort laser pulses. An additional aspect achieves interferences between split subpulses even though the subpulses have different frequencies. Yet another aspect of a laser system employs multiple independent frequency comb phase shaping of a laser pulse. In another aspect, a laser system includes pulse characterization and arbitrary or variable waveform generation through spectral phase comb shaping. In still another aspect of the present laser system, minimal correlation phase functions are used to substantially prevent nonlinear optical processes in the shaped field. In another aspect, a laser system is used for nonlinear optical imaging, micromachining, communications and/or molecular identification. A method of using one or more of these aspects is also provided.
The present laser system is advantageously less expensive than traditional laser systems. For example, phase-only modulators are much less expensive than conventional phase and amplitude modulators. Furthermore, certain aspects of the present system employ split subpulses each having differently shaped characteristics which are much less sensitive to air turbulence and other environmental disturbances than traditional optical methods designed to generate multiple pulses using partially reflective optics. Moreover, the present system is more amenable to the placement of a pulse shaper within or before an amplifier. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.